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  1. #1
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    Copeland 3D, 4D RPM?

    Anyone know the typical RPM on a Copeland 3D,4D reciprocating compressor? Something in the back of my head is telling me 3450 RPM...but I cant remember for sure...1750 also comes to mind, but that seems too slow, more like a fan motor.

  2. #2
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    3D 1370 rpm to 2127
    4D 2386 rpm to 3603
    6D 4136 rpm
    8D 6463 rpm to 7721

    Above min max readings depend on which model is being used

  3. #3
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    Quote Originally Posted by -frozen-ocean- View Post
    3D 1370 rpm to 2127
    4D 2386 rpm to 3603
    6D 4136 rpm
    8D 6463 rpm to 7721

    Above min max readings depend on which model is being used
    Can you show me where you got these figures? I've been looking all day and seem to find 1750 everywhere.

    Thanks

  4. #4
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    All Copeland semihermetics have 4 pole motors which means they run at 1750/1800 RPM. Welded compressors have 2 pole motors and run at 1450/3600 RPM. This is why semi hermetics make a deeper noise when running compared to welded hermetics which make a buzzing noise.


    If you ran any compressor at 7721 RPM, the parts on the inside would quickly be on the outside.

    On a side note, its not possible to run an induction motor above 3600 RPM on a 60 hZ source without a VFD

  5. #5
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    I agree with craig1 on the RPM's.

    It appears -frozen-ocean-'s numbers are actually Copeland's compressor displacements in cu.ft/hr (CFH).

  6. #6
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    Quote Originally Posted by craig1 View Post
    Welded compressors have 2 pole motors and run at 1450/3600 RPM.
    This was supposed to say 3450/3600 RPM

  7. #7
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    Sorry for that, those are displacements in (CFH) not rpm.

  8. #8
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    Quote Originally Posted by Phase Loss View Post
    Anyone know the typical RPM on a Copeland 3D,4D reciprocating compressor? Something in the back of my head is telling me 3450 RPM...but I cant remember for sure...1750 also comes to mind, but that seems too slow, more like a fan motor.
    Interesting question. What prompted this and how would a guy actually verify rpms?
    The views and opinions posted here are my own. They do not reflect the corporate policies of my employer and will most likely get me fired at some point.

  9. #9
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    Quote Originally Posted by engineerdave View Post
    Interesting question. What prompted this and how would a guy actually verify rpms?
    I was setting up some Copeland recip's to run on VFD's. And the VFD's motor parameter settings call for an RPM input.

    RPM's are not listed on the nameplate information.

    I knew there is a calculation for RPM= 120 X supply frequency(Hz) / number of poles

    I just didn't know how many poles are in Copeland's 3D, 4D recip's. It turns out there are 4 poles

    So 120 X 60Hz / 4 poles = 1800 RPM synchronous speed.

    However, induction run motors don't run 100% synchronous speeds, they have a slip...so the RPM is actually around 1750 for a 4 pole motor at 60Hz.

    It's some screw compressors that have 2 poles which run the 3450 RPM

  10. #10
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    Huh. I'd heard that recips were being ramped up & down, don't recall that I've actually seen it anywhere outside the transport world, and they weren't using VFDs. How's it working out for you? The potential for energy savings could be very high, especially in supermarkets. Are you also using the stepper valves as well?
    The views and opinions posted here are my own. They do not reflect the corporate policies of my employer and will most likely get me fired at some point.

  11. #11
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    yeah it's on a supermarket rack system. 1 compressor per suction group. and they are using stepper valves too.

  12. #12
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    Quote Originally Posted by Phase Loss
    yeah it's on a supermarket rack system. 1 compressor per suction group. and they are using stepper valves too.
    Only one compressor per group?

    Hmmm.

    No redundancy?

    I'm already not a fan.

  13. #13
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    I mean, 1 compressor per suction group has a VFD. each suction group has at least 3 compressors total.

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